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Clinical accuracy and safety using the SynchroMed II intrathecal drug infusion pump.

Wesemann K, Coffey RJ, Wallace MS, Tan Y, Broste S, Buvanendran A - Reg Anesth Pain Med (2014 Jul-Aug)

Bottom Line: No deaths, permanent injuries, or unanticipated adverse device effects occurred.The pump accurately delivered intrathecal medication in the clinical setting of this study.Adverse events were similar in nature and severity to those described in the product labeling and literature.

View Article: PubMed Central - PubMed

Affiliation: From the *Medtronic, Inc, Minneapolis, MN; †University of California San Diego, La Jolla, CA; and ‡Rush University Medical Center, Chicago, IL.

ABSTRACT

Background and objectives: We evaluated the infusion accuracy and device-related safety of implantable drug infusion pumps in subjects with chronic pain or severe spasticity.

Methods: Nine centers in the United States enrolled patients receiving intrathecal drug delivery systems to manage chronic pain and/or severe spasticity. Infusion accuracy was assessed at 6 and 12 months by comparing syringe-measured delivered volumes to programmer-predicted volumes. Safety was evaluated through analysis of adverse events. Separate laboratory testing conducted by the manufacturer also evaluated infusion accuracy.

Results: Eighty of 82 enrolled subjects were implanted. Sixty-five and 54 subjects, respectively, were analyzable for accuracy at 6 and 12 months. On average at 6 months, the pumps were measured to have delivered 1% more than the programmed delivery volume. Analyzed on a per-refill basis, the pumps delivered, on average, 2.5% more than the programmed delivery volume. Differences between per-refill means versus per-subject cumulative means were due to limitations in clinicians' ability to precisely visualize single small syringe-volume differences, or possibly incomplete withdrawal of fluid from the pump. Laboratory testing demonstrated a per-refill mean accuracy error of minus 2.4%. Because average observed flow-rate error at 6 and 12 months (1% overinfusion) was derived from pump residual volume measurements by syringe and carried out in a clinical setting, clinical volume ratios were larger than direct volume measurements by weight observed in the laboratory. No deaths, permanent injuries, or unanticipated adverse device effects occurred.

Conclusions: The pump accurately delivered intrathecal medication in the clinical setting of this study. Adverse events were similar in nature and severity to those described in the product labeling and literature.

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Related in: MedlinePlus

Per-refill accuracy ratios, from implant to 6 months after implantation (n = 193 refills). Each refill visit’s data were used to calculate a ratio of observed volume dispensed to programmer-calculated amount dispensed. The individual ratios are plotted and summarized in 2 ways, including the circled outlier values (193 refills) and excluding them (189 refills).
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fig3: Per-refill accuracy ratios, from implant to 6 months after implantation (n = 193 refills). Each refill visit’s data were used to calculate a ratio of observed volume dispensed to programmer-calculated amount dispensed. The individual ratios are plotted and summarized in 2 ways, including the circled outlier values (193 refills) and excluding them (189 refills).

Mentions: Because the per-subject accuracy ratios combine data from multiple visits, an additional analysis was conducted to examine the refill ratio at each visit. Figure 3 illustrates the complete per-refill data, with the accompanying table showing calculations with and without the 4 outlier values (open boxes). The mean per-refill accuracy ratio without outliers was 1.025 (SD, 0.121; mean error of plus 2.5% overinfusion) in 189 refills at varying intervals and volumes. The mean per-refill accuracy is very similar to the mean per-subject accuracy, but there is a wider range and larger SD associated with these single observations. As illustrated in Figure 3, more discrepant accuracy ratios are seen in cases where smaller volumes were dispensed—a situation where small measurement variations or errors can be greater than the volume of drug that was delivered and magnify otherwise small visual (syringe) measurement errors or variations. Incomplete medication removal from the pump may provide an additional explanation of discrepant ratios, particularly those greater than 1.


Clinical accuracy and safety using the SynchroMed II intrathecal drug infusion pump.

Wesemann K, Coffey RJ, Wallace MS, Tan Y, Broste S, Buvanendran A - Reg Anesth Pain Med (2014 Jul-Aug)

Per-refill accuracy ratios, from implant to 6 months after implantation (n = 193 refills). Each refill visit’s data were used to calculate a ratio of observed volume dispensed to programmer-calculated amount dispensed. The individual ratios are plotted and summarized in 2 ways, including the circled outlier values (193 refills) and excluding them (189 refills).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4218763&req=5

fig3: Per-refill accuracy ratios, from implant to 6 months after implantation (n = 193 refills). Each refill visit’s data were used to calculate a ratio of observed volume dispensed to programmer-calculated amount dispensed. The individual ratios are plotted and summarized in 2 ways, including the circled outlier values (193 refills) and excluding them (189 refills).
Mentions: Because the per-subject accuracy ratios combine data from multiple visits, an additional analysis was conducted to examine the refill ratio at each visit. Figure 3 illustrates the complete per-refill data, with the accompanying table showing calculations with and without the 4 outlier values (open boxes). The mean per-refill accuracy ratio without outliers was 1.025 (SD, 0.121; mean error of plus 2.5% overinfusion) in 189 refills at varying intervals and volumes. The mean per-refill accuracy is very similar to the mean per-subject accuracy, but there is a wider range and larger SD associated with these single observations. As illustrated in Figure 3, more discrepant accuracy ratios are seen in cases where smaller volumes were dispensed—a situation where small measurement variations or errors can be greater than the volume of drug that was delivered and magnify otherwise small visual (syringe) measurement errors or variations. Incomplete medication removal from the pump may provide an additional explanation of discrepant ratios, particularly those greater than 1.

Bottom Line: No deaths, permanent injuries, or unanticipated adverse device effects occurred.The pump accurately delivered intrathecal medication in the clinical setting of this study.Adverse events were similar in nature and severity to those described in the product labeling and literature.

View Article: PubMed Central - PubMed

Affiliation: From the *Medtronic, Inc, Minneapolis, MN; †University of California San Diego, La Jolla, CA; and ‡Rush University Medical Center, Chicago, IL.

ABSTRACT

Background and objectives: We evaluated the infusion accuracy and device-related safety of implantable drug infusion pumps in subjects with chronic pain or severe spasticity.

Methods: Nine centers in the United States enrolled patients receiving intrathecal drug delivery systems to manage chronic pain and/or severe spasticity. Infusion accuracy was assessed at 6 and 12 months by comparing syringe-measured delivered volumes to programmer-predicted volumes. Safety was evaluated through analysis of adverse events. Separate laboratory testing conducted by the manufacturer also evaluated infusion accuracy.

Results: Eighty of 82 enrolled subjects were implanted. Sixty-five and 54 subjects, respectively, were analyzable for accuracy at 6 and 12 months. On average at 6 months, the pumps were measured to have delivered 1% more than the programmed delivery volume. Analyzed on a per-refill basis, the pumps delivered, on average, 2.5% more than the programmed delivery volume. Differences between per-refill means versus per-subject cumulative means were due to limitations in clinicians' ability to precisely visualize single small syringe-volume differences, or possibly incomplete withdrawal of fluid from the pump. Laboratory testing demonstrated a per-refill mean accuracy error of minus 2.4%. Because average observed flow-rate error at 6 and 12 months (1% overinfusion) was derived from pump residual volume measurements by syringe and carried out in a clinical setting, clinical volume ratios were larger than direct volume measurements by weight observed in the laboratory. No deaths, permanent injuries, or unanticipated adverse device effects occurred.

Conclusions: The pump accurately delivered intrathecal medication in the clinical setting of this study. Adverse events were similar in nature and severity to those described in the product labeling and literature.

Show MeSH
Related in: MedlinePlus